Condenser tube



Oct. 15, 1935.

o. A. BOSSART ET AL 2,017,201

CONDENSER TUBE 2 Sheets-Sheet 1 Filed Nov. 2'7, 1931 fizz/6712 071; 02/0J7. 5055427"? and 577207346X 613" erficzrd'i Patented Oct. 15, 1935UNITED STATES CONDENSER TUBE Otto A. Bossart and Emanuel G. Eberhardt,

Racine, Wis., assignors to Modine Manufacturing Company, Racine, Wis, acorporation of Wisconsin Application November 27, 1931, Serial No.577,560

- 7 Claims. (01. 257262) The invention relates to heat exchange deviceswhich include in their construction tubular elements through which aliquid is circulated to v transmit heat from the liquid circulatingthrough the tubes and the fluid circulating through the heat exchangedevice.

The invention primarily relates to improvements in tubes employed indevices such as those above referred to and has among its objects to 20provide the tube with means whereby the heat exchanging emciency of thetube is increased. Another object ofthe invention is to construct 'thetube in a manner to provide restrictions 'in the passage of the tube atintervals of the length 15- of. the tube, the restrictions providingmeans for creating turbulence of the liquid passing through the tubesand providing means for increasing the velocity of the fluid circulatingthrough the tube.

It is an object of the invention to provide tubes at which arerelatively narrow or elongated in cross section with means capable offunctioning in the Specifically, the invention has as an objectindenting the one or both walls of a relatively fiat tube at intervalsof its length to provide inwardly projecting ribs which extend crosswiseof the tube in spaced relation to the opposite wall of the tube in thepath of the liquid flowing through the tube to thereby provide aturbulence creating rib and 3% a passage at the rib which provides meansat intervals of. the length of the tube for increasing the velocity ofthe liquid and creating turbulence to thereby displace the liquidcontacting with the I inner portion of the tube and present another 4%portion thereto to this portion of the tube to iagiltate cooling of thefluid circulating through the it is an object to arrange thesetransverse depressions or ribs in various positions of angularity.

It is another object of the invention to provide a construction capableof accomplishing the above advantages without increasing the material ofthe tube.

Another object of the invention is to employ the w means for obtainingthe above and other advantages to strengthen the tube.

The invention also has as an object to provide a construction capable offunctioning in the manner m above referred to which will notmateriallyinter- $9 fere with contact between the tubes and heatradiating fins associated with the tubes.

Another object of the invention is to arrange the restrictions in thepassages of the tubes so that they are located upon opposite sides ofthe central m plane of the interior of the tube located" midway betweenthe side walls thereof to thus facilitate agitation of the fluid andconsequently the rate of heat exchange.

The invention has these and other objects, all

of which will be explained in detail and more 5 7 of the invention asexpressed or defined in the appended claims forming a part hereof.

In the drawings, Fig. 1 is a front view of a portion of a heat exchangedevice having the invention applied thereto;

Fig. 2 is a section taken on the line 2-2 of Fig. 1 showing a fragmentof one of. the tubes as shown in Fig. 1;

Fig. 3 is a perspective view partly in section of one of the tubesemployed in the structure shown in Fig. 1; r

Fig. 4 is a view similar to Fig. 3 showing a modified arrangement whichmay be employed;

Figs. 5 and 6 are respectively side views of modified arangements whichmay be employed to I accomplish the invention;

Fig. '7 is a transverse section of a tube constructed according tothe'invention;

Fig. 8 is a section taken on line 8-8 of Fig. 5;

Fig.9 is a side view of a portion of a tube illustrating a structure inwhich the indentations on opposite sides of the tube are inclined in thesame direction, the indentations of one side of the tube being locatedbetween a pair of indentations provided in the opposite side of thetube;

Fig. 10 is a side view of a portion of a tube showing the indentationson one side of the tube, arranged at one angle, the indentations in theopposite side arranged at another angle, the in- 40 dentations onopposite sides of the tube crossing each other;

Fig. 11 is a side view of a portion of a tube in which the ribs arearranged in staggered relation; and

Fig. 12 is a side view of a tube having heat radiating fins associatedtherewith.

invention as illustrated in Fig. 1 is shown as applied to a heatexchange device having tanks it and l 9 located at opposite ends of thetubes I2, it being understood that the tubes communicate with the tanksand thus provide for'clrculation of liquid from one tank to the other.The tubes of the heat exchange device may, as illustrated, be providedwith heat radiating fins I3 to fur- 5 ther assist in causing a rapidtransfer of heat from the liquid circulating through the tubes and theair circulating between the tubes.

Each of the tubes i2 is preferably formed of sheet material which isfashioned-to provide a 50 tube which is relatively fiat or elongated incross section as shown in Fig. 7 to thus provide relatively fiat sidewalls l4 and 15, each of which is, in the present instance, providedwith a plurality of spaced depressions which extend crosswise of theformed thereby are designated n. n will be noted that the opposite wallsuch as i5 is also provided with a plurality of recesses providinginwardly projecting ribs designated l9 which extend inwardly toward thewall It in a manner similar to those described in connection with therecesses It. It will also be noted that the ribs ll of one wall arearranged in spaced relation on opposite sides of a rib such as l9 formedby the depression in the opposite ,wall and, therefore, fluidcirculating through the tube will be caused to travel a circuitous paththrough the tube and will engage the ribs such as H and I9 and increaseits velocity and create turbulence of the fluid. It is evident thatturbulence of the liquid which is created by the ribs causes the liquidcirculating through the tube to act upon the liquid engaging the innerface of the portions 2| of the tubes and will cause its removal and thuspermit another portion of the liquid to be presented to the coolingaction of these portions of the tube and thusfacilitate cooling of theliquid.

It will be further noted that space's or pockets such as are producedand that these pockets are located upon opposite sides of each of theribs formed by the depressions which will thus provide a space adjacenteach of the ribs to which.

liquid is introduced through the passage l8 at an increased velocitycausing turbulence to the liquid and subjecting said liquid while underturbulence .to the cooling action of the surfaces 2! which aremaintained at a cooling temperature by virtue of air circulating incontact therewith. It is evident that the ribs add to the strength ofthe tube to resist forces created internally of the tube and furtherthat the means for creating turbulence is 1 produce ribs respectivelydesignated 26 and 21, it

being understood that a space is produced between the rlbs so that fluidmay circulate therebetween and travel through the tubes. It will benoted that in the modified structure shown in Fig. 4, the depressedportions which form the ribs 26 and 21 are located opposite each other,thus differing in structure from that illustrated in Fig. 2 in which theribs I1 and IS in opposite walls are arranged with the rib of one wallarranged between a pair of ribs provided in the other wall whichdisposes the passages l8 upon opposite sides of the central longitudinalplane of the interior of the tube. It will be further noted that thedepressions l1 and I9, and 24 and 25 formed in the structuresillustrated in Figs. 3 and 4 are arranged at right angles to the lengthof the tube, it being understood that the depressions may be arranged inthis manner or arranged at an obtuse angle as illustrated in Figs. 5 and6. In Fig. 5, the depressions 28 are located at an angle other than aright angle and thus difier from the structure shown in Figs. 3 and 4,it being understood that the ribs formed by these depressions may bear arelation to each other as illustrated in Fig. 3 or Fig. 4.

The'structure shown in Fig. 6 also contemplates the utilization of atube which is relatively flat in cross section, however, differs fromthe structure shown in Fig. 5 and others in that the opposite sides ofthe tube are respectively provided with depressions 29 and 30, thedepressions 29 and 30 being arranged at an angle to each other. 10 It isfurther understood that the tube may be formed of sheet material whichis bent as shown in Fig. 7 with the edges soldered, brazed or otherwisesecured to complete the tube. When the tube is formed of sheet materialand subsequently bent, 15 the depressions which form the ribs and a wallof the relatively long narrow passages are produced in the sheet priorto forming the tube they being located in the sheet so that when thesheet is bent one or the other of the structures dis- 2 closed willresult. The structure illustrated in Fig. 9 contemplates arranging thedepressions 3| in one side of the tube and providing depressions such as32 in the V opposite side of the tube with the depressions on 25opposite sides inclined in the same direction, the depression such as 32on one side of the tube being located between the pair of depressionssuch as 3|, thus difiering from the structure shown in Fig. 5 in whichthe depressions are arranged 30 at an incline, however, opposite eachother as illustrated in Fig. 4. 5

In Fig. 10, the depressions such as 33 on one side of the tube arearranged at an incline relatively to the depressions such as 34 providedupon 35' the opposite side of the tube, in other words, the depressions33 and 34 in the structure shown Fig. 10 cross each other.

In the arrangement shown in Fig. 11, the depressions such as 35 and 36on one side of the tube are arranged in staggered relation and formed,respectively, at opposite sides of a longitudinal center line locatedmidway between the edge portions of the tube, it being understood thatthe depressions 31 and 38 on the opposite side of this i5- tube are alsostaggered and formed, respectively, at opposite sides of the center linebetween the edge portions of the tube, however, these last mentioneddepressions may be arranged relatively to the depressions 35 and 36 asshown in 60 dotted lines in Fig. 11 or, the depressions such as 31 and38 may be arranged opposite the depressions 35 and as hereinbeforedescribed in connection with other structures.

One of the advantages of the structure is that the surface contactlossbetween the tubes and fins is minimized this feature being illustratedin Fig. 12, from an inspection of which it can be seen that the fins l3contact witha substantial portion of the tubes and therefore the heatconducting eihciency of the fins and tubes will not be materiallyinterfered with or reduced, it being manifest that a substantial portionof the tube is in contact with the major portion of the crosssectionalarea of the fins. Since the depression forming the rib is distributedover a number of the fins, the major portion of the tube adjacenttheflns will contact with the fin.

From the foregoing description of the various structures, it is manifestthat the invention lends itself to.the production of a tube having a.plucirculating through the tube and that this is accomplished withoutadding to the material of the tube. It is further manifest that byarranging the recess or rib provided in one side of the tube relativelyto a flat portion such as 2| of the opposite side of the tube thatrelatively long and narrow restricted passages are provided uponopposite sides of the central longitudinal plane of the interior of thetube, which will assist in creating turbulence and velocity.

It is evident that turbulence of the fluid is further assisted becauseof the offset relation of the restricted passages I8 which willalternately cause the fluid to be directed towards the sides of theinterior of the tubes, which change of course will cause agitation andturbulence of the fluid and thus increase the rate of heat exchangebetween the fluid circulating through the tube and the air circulatingon the outside of the tube.

It is further manifest that as the fluid circulates through the tubesand is agitated, that this agitation causes a scrubbing action to beapplied to the fluid adhering to the interior of the walls of the tubeswhich will thus remove this part of the fluid and allow a differentportion of the fluid to be presented to the cooling effect of the airtraveling across the tube. It is further manifest that the arrangementdoes not materially reduce area of contact between the fins and thetubes which also is of advantage since it tends to maintain the rate ofheat exchange between the fluid circulating through the tubes and theair engaging the fins and tubes.

In addition to the above enumerated advantages, it can be seen that theribs provide means which will addstrength and resistance to pres- .sureinternally of the tube and furthermore that no obstruction is presentedwhich will interfere with passing said tubes through apertures in thefins.

Having thus described the invention, what we claim and desire to coverby Letters Patent is:

1. In a heat exchange device, a plurality of in dependent parallel sheetmetal tubes adapted for the passage of a fluid'therethrough, each tubehaving a pair of substantially parallel walls, a plurality of inwardlyextending transverse indentations formed in one wall of said tube instaggered relation and spaced from each other longitudinally of thetubev and extending transversely to the direction of flow of fluidthrough the tubes, each indentation in one wall cooperating with theopposite wall of said tube to form a transverse restriction in thepassage through said tube offset from the central plane of the tube.

2. In a heat exchange device, a plurality of independent parallel sheetmetal tubes adapted for the passage of fluid therethrough, each tubehaving a pair of substantially parallel walls, a plurality of inwardlyextending transverse projections upon the inner side of each wall ofsaid tube and arranged in staggered relationship at opposite sides ofthe center line thereof and spaced from each other longitudinally of thetube and extending transversely to the direction of flow of fluidthrough the tubes, each of the projections on the respective wallscooperating with the opposite wall of said tube to form a transverserestriction in the passage through said tube, said restrictions beingalternately positioned at opposite sides of the center line of saidtube.

3. In a heat exchange device, a plurality of independent parallel sheetmetal tubes adapted for the passage of fluid therethrough, each tubehaving a pair of substantially parallel walls, a plurality of inwardlyextending transverse projections upon the inner side of each wall ofsaid tube spaced transversely and longitudinally from each other andfrom the projections upon the opposite wall of said tube and extendingtransversely to the direction of flow of fluid through the tubes, eachof the projections on the respective walls cooperating with the oppositewall of said tube to form a transverse restriction in the passagetherethromgh, said restrictions being alternately positioned atoppositesides of the central plane of said tube.

4. In a heat exchange device, a plurality of independent parallel sheetmetal tubes adapted for the passage of fluid longitudinallytherethrough, each tube having a pair of substantially parallel walls, aplurality of inwardly extending transverse projections upon the innerside of one wall of said tube spaced from each other longitudinally ofthe tube and extending transversely to the direction of flow of fluidthrough the tubes, each of said projections cooperating with a flatportion upon the opposite wall of said tube to form a transverserestriction of substantially uniform width in the passage through thetube and ofiset from the central plane thereof.

5. In a heat exchange device, a plurality of independent parallel sheetmetal tubes adapted for the passage of fluid therethrough, each tubehaving a pair of substantially parallel walls, a plurality of staggeredinwardly extending transverse indentations formed in each wall of saidtube and spaced from each other longitudinally of the tube and extendingtransversely to the di- I rection of flow of fluid through the tubes,each indentation in each wall cooperating with the opposite wall of saidtube to form a transverse rethe passage of fluid therethrough, each tubehaving substantially parallel walls, a plurality of staggered inwardlyextending transverse indentations formed in each wall of said tube andspaced from each other and from the indentations formed in the oppositewall longitudinally of the tube and extending transversely to thedirection of flow of fluid through the tubes, each indentation in eachwall cooperating with the opposite wall of said tube to form atransverse restriction in the passage therethrough.

'7. In a heat exchange device, a plurality of independent parallel sheetmetal tubes adapted for the passage of fluid therethrough, each tubehaving a pair of substantially parallel walls, a plurality of inwardlyextending transverse indentations formed in each wall of said tube andin staggered relation at opposite sides of the longitudinal center linethereof, the said indentations being spaced from each other and from theindentations formed in the opposite wall longitudinally of the tube andextending transversely to the direction of flow of fluid through thetubes, each indentation in each wall cooperating with a flat portionupon the opposite wall of said tube to form a transverse restriction inthe passage 7 EMANUEL G. EBERHARDT. 75

